This proposal is designed to study the structural differences between tRNA in normal human tissues and those in malignant human cells with emphasis on phenylalanine tRNA in these human tissues. The objectives and methods are: (1) to study the chromatographic properties of tRNAphe in human liver, brain and malignant tissues. Methods will be reverse phase column chromatography (RPC-5) under various conditions. (2) to prepare these species of tRNAphe in pure form so that sequence analysis on these tRNAs will be possible. Sequencing techniques will be enzymatic degradation and dephosphorylation, periodate oxidation, 3H- KBH4 reduction, thin layer chromatography, and "fluorography". (Sequence work will be submitted in a separate application by Dr. Randerath of Baylor College of Medicine, Houston, Texas.) (3) to carry out comparative studies on tRNAs specific for other amino acids in normal and malignant human cells.